docs: def asset(self, asset_id, query=None):
          """Fetches an Asset by ID.
  
          API Reference: https://www.contentful.com/developers/docs/references/content-delivery-api/#/reference/assets/asset/get-a-single-asset
  
          :param asset_id: The ID of the target Asset.
          :param query: (optional) Dict with API options.
          :return: :class:`Asset <Asset>` object.
          :rtype: contentful.asset.Asset
  
          Usage:
              >>> nyancat_asset = client.asset('nyancat')
              <Asset id='nyancat' url='//images.contentful.com/cfex...'>
          """
  
          return self._get(
              self.environment_url(
                  '/assets/{0}'.format(asset_id)
              ),
              query
          )